Why do some lines in the poetic translation of the Odyssey end with a period and others with a comma? What is different about what those two graphical elements convey? Because some of them are not complete sentence

Use a period
for a full stop. In poetic terms, a period that occurs at the end of the line is referred to as an end-stop. An end-stopped line calls for a definite pause in the recitation of the poem, a place to take a full breath before continuing to the next line.

Using a comma
Punctuation is a very personal thing in poetry and, I daresay, prose. ... It's not necessary in between or at the end of every single line, in most cases, and it's even possible to write a poem without one punctuation point and still keep it effective.

Graphic elements show relationships, hierarchy, and emphasis visually. They include backgrounds, banners, glass, aggregators, separators, shadows, and handles. ... Graphic elements are usually not interactive. However, separators are interactive for resizable content and handles are graphics that show interactivity.